Pacific Legal Foundation attorney Damien Schiff, in a June 14 debate in Sacramento staged by the conservative Federalist Society, laid out his case, to be argued before the federal Ninth Circuit Court of Appeals later this year.

The fish exists only in the Sacramento-San Joaquin Delta, and has no commercial value, Schiff said. Therefore the feds cannot regulate it under the Constitution's interstate-commerce provisions, which have formed the basis of the ESA's constitutionality.

The tiny smelt has become the focus of wrangling over the Delta, the hub of the state's water distribution system. Environmentalists point to the smelt's value as an "indicator species" gauging the estuary's health.

But agriculture and other industries have sought greater consideration of economic impacts as drought and water cutbacks for protecting fish have escalated in the past three years, resulting in widespread fallowing of farmland in the San Joaquin Valley.

PLF appealed its case to the Federal Ninth Circuit Court of Appeals after Fresno Judge Oliver Wanger upheld the smelt protections in December.

Schiff argued that the regulated activity -- the killing of smelt -- does not affect commerce, because the fish has no commercial value.

Rather it's the opposite, Schiff said. Commerce -- farming along with most other commercial activity in parts of the state that use Delta water -- result in the killing of fish, because the powerful pumps that deliver water are killing smelt.

And since nearly any activity can be somehow connected to commerce, federal power becomes limitless, Schiff argued.

"That little move allows the federal government to regulate everything," Schiff said. "That is ridiculous, and that is not what the Supreme Court has said is appropriate."

But Richard Frank, a lecturer at University of California-Berkeley, said the court would reject that argument because the ESA as a whole has been shown to "substantially" impact interstate commerce. The connections are varied, including trade in declining species, Frank said.

Like judges in previous cases, Wanger upheld the ESA, saying the law as a whole impacts interstate commerce and cannot be picked apart.

"Every reported case that has addressed the question has upheld the Endangered Species Act against Commerce Clause-based challenges," Frank said.

Courts have decided that federal protection cannot be allowed only when a species has commercial value, then revoked "once economic exploitation has driven that species so close to the brink of extinction that it desperately needs the government's protection," Frank said.

Therefore the courts have decided in several cases that Congress can regulate a "purely local ... class of activities" that impact interstate commerce, Frank said.

"And the Endangered Species Act, looked at in the aggregate, certainly does so," he said.